Fiber optic cable is increasingly being used for telecommunications and other data forwarding purposes. Such cable allows a large capacity increase relative to the use of copper or aluminum wire and is particularly valuable for increasing capacity for digital and analog communications. The location of such cable, however, is of considerable importance because if the fiber optic cable is damaged or severed, extensive telecommunication failure can occur.
In order to prevent damage to the telecommunications cable, the cable is preferably buried. Right of way is difficult to obtain and is expensive in any event. To avoid the problems with right of way and in order to better protect the cable, the cable has been laid in railroad beds. This is advantageous in that the right of way has already been obtained and that railroads have their own benefits in allowing the burial of fiber optic cable so that the cable might also be used for their own communications purposes. Likewise, the network of rail lines is extensive so that cable can be laid to virtually any location where there is a significant population base.
The cable is typically laid using a rubber tired railway plow such as that plough disclosed in our U.S. Pat. No. 5,596,822 dated Jan. 28, 1997. The plow there disclosed, however, suffered from various disadvantages.
First, the plow was mounted on the front end of the rubber tired vehicle and was designed to plow on only one side of the track on which the vehicle is mounted. In order to plow on the opposite side of the track on which the plow moved, the plow was required to be manually removed from the mounting bracket on the forward end of the vehicle by physical detachment of the plow. The plow was then manipulated usually with a front end loader so that it could be positioned on a second mounting bracket on the opposite side of the vehicle. Then, the plow was remounted on the second mounting plate. Such a method was time consuming, required a plurality of operators and was quite inefficient.
Second, the railway plow according to the '822 patent had a single set of railwheels mounted on the forward end of the plow. In the event the plow hit something hard in the ballast or in the overburden during the plowing process, the impact force would be conveyed back to the plow itself and could result in the single pair of railwheels leaving the track. This necessitated the remounting of the vehicle on the track as well as repositioning the plow during such remounting. This process was time consuming and inefficient.
Third, since a circuit is needed between the rails to provide a signal to the roadcrossing signals at a crossing location and since it is not desirable to close the gates or maintain the bells or other noises at such crossing locations during cable burying or excavation operations in the vicinity of such crossing, insulation within the railwheels was needed to prevent the road crossing signals from being initiated by the operation of the nearby railplow, excavator or other equipment. Prior insulation used in the railwheels had a very short lifespan because the impact forces, particularly during the plowing operations, are significant. The premature replacement of the insulation within the railwheels was expensive because downtime of equipment was necessary.
Fourth, the railway plow according to the '822 patent was maintained in its vertical position on the track by the use of a rear high rail. This high rail, however, provided no input to the profile of the railway being worked on. For example, as the machine approached a crossing, the rubber tires would tend to raise the plow with the railwheels leaving the rails. This is disadvantageous since it is time consuming to reconfigure the vehicle on the rails.
Fifth, there is some difficulty in positioning the rubber tired vehicle according to the '822 patent on the rails of the railway. This is so because the vehicle is of the articulated type and movements of the vehicle under certain conditions is difficult to carry out with the result that positioning the vehicle on track, particularly where the track is located in an elevated location, is a more tedious proposition that otherwise would be the case.
Sixth, it may be the case that the overburden is not easily penetrated by the plow if the overburden is rock or rocky material as in mountainous or shield operating conditions. In this event, excavation of the overburden together with the ballast of the railway will be necessary prior to passage by the plow. In excavating the railway, the overburden and ballast is normally placed beside the track is a convenient location and is replaced after the excavating operation whereupon when the plow reaches the excavated location, it will easily pass through the overburden and properly bury the cable. However, the overburden may be located in an area where it is not easily deposited beside the track such as in tunnels or mountainous passes where there is no room available to place the overburden being removed. In this event, the excavated overburden needs to be removed and deposited at a location far removed from the area being excavated. This is time consuming and inefficient, particularly so where the overburden is to be replaced immediately following its excavation.
Seventh, in the event that an excavating vehicle is used to remove the overburden and ballast, the excavating vehicle must be moved to the next location where excavation is to occur. Moving the excavating vehicle under its own power is slow and requires manpower. This is inefficient and expensive.